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Linux Tutorial Series

Linux Tutorial Series – 172 – Compiling a program – what does that even mean?

Here is the video version, if you prefer it:

In this article, I will mention a couple of key terms related to the Linux desktop. (Ward, 2014)⁠

The first one is the X Window System. It is just a framework – think of it as “bare bones” of a GUI (Graphical User Interface) environment. It is up to other programs to build upon this “bare bones” and construct the graphical user interface. (“X Window System,” n.d.)⁠

Desktop environment is a package that allows for cooperation of different applications in a graphical sense. For example, application A tells application B that it is 50% done with a certain task and the application B displays that on its status bar. GNOME and Unity are examples of a desktop environment.

Some other terms and their explanations: Window managers arrange windows on the screen and provide interactive decorations like title bars that allow the user to move and minimize windows. Common elements on desktop applications (such as buttons and toolbars) are called widgets. Toolkits are used to provide widgets because that speeds up development.

That’s it for this post. I never dug really deep into Linux desktop, but if you ever encounter any one of these terms, I hope you have some more clarity as to what they mean.

Hope you learned something useful!

References

Ward, B. (2014). How Linux Works: What Every Superuser Should Know (2nd ed.). No Starch Press. Pages 297-299

X Window System. (n.d.). Retrieved February 15, 2020, from https://en.wikipedia.org/wiki/X_Window_System

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Linux Tutorial Series

Linux Tutorial Series – 171 – Linux desktop – a couple of key terms

Here is the video version, if you prefer it:

In this article, I will mention a couple of key terms related to the Linux desktop. (Ward, 2014)⁠

The first one is the X Window System. It is just a framework – think of it as “bare bones” of a GUI (Graphical User Interface) environment. It is up to other programs to build upon this “bare bones” and construct the graphical user interface. (“X Window System,” n.d.)⁠

Desktop environment is a package that allows for cooperation of different applications in a graphical sense. For example, application A tells application B that it is 50% done with a certain task and the application B displays that on its status bar. GNOME and Unity are examples of a desktop environment.

Some other terms and their explanations: Window managers arrange windows on the screen and provide interactive decorations like title bars that allow the user to move and minimize windows. Common elements on desktop applications (such as buttons and toolbars) are called widgets. Toolkits are used to provide widgets because that speeds up development.

That’s it for this post. I never dug really deep into Linux desktop, but if you ever encounter any one of these terms, I hope you have some more clarity as to what they mean.

Hope you learned something useful!

References

Ward, B. (2014). How Linux Works: What Every Superuser Should Know (2nd ed.). No Starch Press. Pages 297-299

X Window System. (n.d.). Retrieved February 15, 2020, from https://en.wikipedia.org/wiki/X_Window_System

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Linux Tutorial Series

Linux Tutorial Series – 170 – The scp command

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In order to copy files from one computer to another, use scp. (Shotts, 2019)⁠

To copy a file from your machine to the server, use the following syntax:

scp localFile username@remotehost:/directory

More scp examples can be found here: (“Example syntax for Secure Copy (scp),” n.d.)

Thank you for reading!

References

Example syntax for Secure Copy (scp). (n.d.). Retrieved February 15, 2020, from http://www.hypexr.org/linux_scp_help.php

Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Page 238-239

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Linux Tutorial Series

Linux Tutorial Series – 169 – The ssh command

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To connect to a remote host (remote computer), use ssh. (Shotts, 2019)⁠ ssh will allow you to use the command line as if you were physically present on the other computer’s Terminal. The computer you are connecting to needs to run ssh server and you need to be running ssh client.

Command usage:

ssh host

or:

ssh username@host

if you want to connect with a different username other than the username on your local machine.

Note: You most likely won’t be using this if you are a desktop user, but if you are a programmer, you will most likely at least sometimes be required to connect to a machine remotely.

Thank you for reading!

References

Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Pages 234-238

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Linux Tutorial Series

Linux Tutorial Series – 168 – nmtui – If you ever need to configure network interfaces

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If you ever need to edit connections, you can use nmtui. It came preinstalled with my Debian 10. It allows you to set your IP, among other things. I used it only once, but if you want more information, (and you can assume what I will say next) Google will give it to you.

Thank you for reading!

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Linux Tutorial Series

Linux Tutorial Series – 167 – The traceroute command

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The traceroute command is used to see the route of a packet sent from your computer to the destination computer. (Shotts, 2019)⁠ Remember, packets are just small chunks of data sent over the computer network.

An example of its usage:

mislav@mislavovo-racunalo:~$ traceroute www.google.com

traceroute to www.google.com (172.217.16.100), 30 hops max, 60 byte packets

1 speedport.ip (192.168.1.1) 4.490 ms 5.863 ms 7.275 ms

2 172.27.99.1 (172.27.99.1) 12.774 ms 15.713 ms 18.709 ms

3 172.28.238.67 (172.28.238.67) 21.826 ms 25.468 ms 26.822 ms

4 hdr11-gut21.ip.t-com.hr (195.29.224.145) 30.081 ms 33.572 ms hdr11-gut21-2.ip.t-com.hr (195.29.225.121) 35.273 ms

5 gtr11-hdr11.ip.t-com.hr (195.29.3.46) 37.511 ms 40.042 ms 42.717 ms

6 72.14.204.128 (72.14.204.128) 51.135 ms 13.224 ms 13.562 ms

7 74.125.242.241 (74.125.242.241) 17.242 ms 74.125.242.225 (74.125.242.225) 19.994 ms 22.164 ms

8 72.14.239.195 (72.14.239.195) 23.811 ms 27.805 ms 72.14.239.201 (72.14.239.201) 32.334 ms

9 bud02s25-in-f4.1e100.net (172.217.16.100) 32.541 ms 33.624 ms 35.218 ms

We can see all of the points that my packets visited until it finally reached www.google.com. If you were to see asterisks (*) instead of concrete information in any of the steps, that means that the router (the part of the networking hardware that routes the packets) is configured not to give away identifying information. Here this is not the case.

Thank you for reading!

References

Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Pages 227-228

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Linux Tutorial Series

Linux Tutorial Series – 166 – The ping command

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The ping command is used to check if your Internet connection is working properly.

Here is its syntax: (Shotts, 2019)⁠

ping internetAddress

An example:

mislav@mislavovo-racunalo:~$ ping www.google.com

PING www.google.com (172.217.16.100) 56(84) bytes of data.

64 bytes from bud02s25-in-f4.1e100.net (172.217.16.100): icmp_seq=1 ttl=55 time=14.2 ms

64 bytes from bud02s25-in-f4.1e100.net (172.217.16.100): icmp_seq=2 ttl=55 time=16.9 ms

^C

--- www.google.com ping statistics ---

2 packets transmitted, 2 received, 0% packet loss, time 3ms

rtt min/avg/max/mdev = 14.244/15.552/16.861/1.314 ms

Focus on the 0% packet loss here. If it was 100% packet loss, then I would know something is wrong with my network.

Thank you for reading!

References

Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Pages 226-227

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Linux Tutorial Series

Linux Tutorial Series – 165 – The ip command

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The ip command is used to display information about network interfaces (among other things). (Shotts, 2019)⁠ Your network interface is the hardware within your computer which allows it to communicate via a computer network.

Here is an example of the ip command:

mislav@mislavovo-racunalo:~$ ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo

valid_lft forever preferred_lft forever

inet6 ::1/128 scope host

valid_lft forever preferred_lft forever

2: enp2s0f1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000

link/ether 98:28:a6:1b:c0:18 brd ff:ff:ff:ff:ff:ff

3: wlp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000

link/ether 42:00:d9:4a:1e:45 brd ff:ff:ff:ff:ff:ff

inet 192.168.1.3/24 brd 192.168.1.255 scope global dynamic noprefixroute wlp3s0

valid_lft 81396sec preferred_lft 81396sec

inet6 fe80::5ce3:3fee:50bf:4d6f/64 scope link noprefixroute

valid_lft forever preferred_lft forever

First note that I have 3 network interfaces – each start with numbers 1 to 3. Also note that, in their first line, they have the keyword state following the word UNKNOWN, UP or DOWN. UP means that the interface is currently enabled. If you want to know your IP address, look up the inet field of the interface (before the forward slash). My IP address is 192.168.1.3. This is my local IP address, not my global IP address. You can Google “how to find out my global IP address” if you ever need to find your global IP address.

A side note: The ifconfig command was used for the purpose of finding out your local IP address before, but now it has been depracated. I couldn’t have used it on my Debian 10.

Thank you for reading!

References

Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Pages 228-229

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Linux Tutorial Series

Linux Tutorial Series – 164 – Computer networks – the very basics

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Today let’s talk about the very basics of computer networks.

First of all, let me say that the field of computer networks is very vast. I had 2 college courses dealing with computer networks and I feel like we barely scratched the surface of the topic. So what I will do is try to introduce you to all of the concepts in computer networks we will need to understand the commands that will follow and no more. I will also be relatively broad in my descriptions and will not nitpick the details; again, just enough knowledge to cover the later commands. Computer networks could warrant a post series in it of itself and I would have to do it after extensively reviewing the subject matter.

A computer network is consisted of layers. Each time you are sending some data over a network, your data has to pass through these layers in your computer, and, at the destination computer, it also has to pass through the same layers, but in reverse order.

Each layer has a different function and addresses different concerns. There is a layer we are particularly interested in, called the network (or the internet) layer. On this layer, each device connected to a network has its own unique IP (Internet Protocol) address. This enables network devices to communicate with each other – they address each other using IP addresses. When sending data over a computer network, that data is most likely chunked into little pieces. Each one of these pieces traveling on the computer network is called a packet. Packets travel through the nodes of the computer network until they reach its destination. Packets are forwarded by routers, a piece of network hardware that routes packets to where they should go in order to reach their destination.

There is a difference between IP addresses – there is your local IP address, which is what computers within your local network use and there is your global IP address, unique to you globally. Think of it like this – if someone in your house wants to talk to your computer via a computer network, it uses the local IP address. If, on the other hand, someone wants to talk to your computer outside of your house, they have to globally address you. The same way when a family member calls your name – you know they are calling you. However, if you are to receive a letter from the police station and someone uses your name, they will use your full name, or even some identification number unique to you, so you can be sure that they are addressing you.

I think we have all it takes to look at some of the most basic network commands. Let’s take a look at them in the following posts.

Thank you for reading!

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Linux Tutorial Series

Linux Tutorial Series – 163 – Time

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A quick word on time in Linux – incorrect time can cause web browser issues. (“How to troubleshoot time related errors on secure websites,” n.d.)⁠ Many distributions support using the NTP (Network Time Protocol) daemon to maintain the time using the remote server. (Ward, 2014)⁠ You can also mangle with timezones, but I never needed this. My advice: Don’t mangle with time unless you really need to (such as when you find the error above). I never had to.

Thank you for reading!

References

How to troubleshoot time related errors on secure websites. (n.d.). Retrieved February 13, 2020, from https://support.mozilla.org/hr/kb/troubleshoot-time-errors-secure-websites

Ward, B. (2014). How Linux Works: What Every Superuser Should Know (2nd ed.). No Starch Press. Pages 157-159